Can you tell me what is a hyperbaric chamber and its functions for treatment?

A hyperbaric: chamber is a chamber containing(single diver/patient) or providing (multiple divers/patients) a 100% oxygen environment used to treat decompression illness, CO poisoning, osteo-radionecrosis, diabetic or ischemic ulcers, failing grafts as well as other difficult to treat wounds.

Hyperbaric oxygen: There are several medical indications for hyperbaric oxygen. You should pray that you have none of these conditions. They include scuba diving injuries, diabetic foot infections (severe), radionecrosis of the jaw, just to name a few. The indications are very specific. There are many 'off-label' uses but none of these have been established.

High oxygen delivery: Hyperbaric oxygen treatment is when a patient breaths 100% Oxygen under a pressure of 2.0 to 2.45 atmospheres (equivalent to 33-45 feet of sea water). It has 14 approved indications some are: DM ulcers, radiation injuries, carbon monoxide poisoning, problem wounds, bone infection, severe infections, even some form of hearing loss. Off label uses include autism, chronic regional pain and others.